In the key-cutting field, there are two types of machines for cutting replacement keys. One is a "duplicator" which utilizes an existing key as a pattern. The other is a "code cutter" which does not require an existing cut key but instead utilizes a key or lock number and coded information to establish the proper settings on the key cutting machine.
The standard equipment used by locksmiths is a duplicating machine having rotary filing or milling cutters for cutting the key blanks. The key duplicating machine has three basic parts comprising a pair of vises coupled together and moving in unison, a key guide, and a cutter wheel. One vise holds the original key and the other holds the key blank. The key guide reproduces the profile of the original key on the blank. The cutter wheel notches the key blank to the desired depth on orders from the key guide. The key duplicating machines operate on 110-volt AC or 12-volt DC current and are sometimes carried in a van or service truck.
By employing a set of coded depth keys, a locksmith can cut key blanks for a cylinder lock according to a code supplied by the lock manufacturer. Coded spacing keys are also employed for this purpose. The depth keys make it possible for the locksmith to use his duplicating key cutter to change the pin tumblers and keys of a cylinder lock according to code.
While code cutting on duplicating machines is time consuming and inefficient, some locksmiths have found this to be the most practical way to conduct their business. Heretofore there were no inexpensive portable house-key cutters which suited the needs of the ordinary locksmith. Small portable code cutters of the type disclosed, for example, in U.S. Pat. No. 3,633,451, with a reciprocating shear type punch, which have been used extensively for many years to cut automobile keys, are quite unsuitable for cutting house keys. Special rotary cutting machines are available for code cutting of house keys, but their size and cost make them unattractive to many locksmiths.** FNT ** See the electric rotary code cutting machine of U.S. Pat. No. 4,521,142.
In recent years a special house-key code cutter was made available for certain brands of pin-tumbler cylinder locks and used for shear cutting of keys at some of the larger motels and apartments with a need for frequent key changes. However, this did not meet the needs of typical locksmiths servicing many different brands of locks. Also the code cutter could not match the precision of typical duplicating key cutters.
This special house-key code cutter lacked versatility and was not cost effective because of its limited utility. It did not provide the convenience and speed of the auto-key code cutters, exemplified by U.S. Pat. No. 3,633,451, and could not be used in connection with all of the common brands of cylinder locks. It was unacceptable to most locksmiths because of the need to purchase a number of separate key cutters to handle a number of different brands of locks. Too many different code cutters were required for the typical locksmith servicing a large number of different business establishments. Another problem with the special house-key cutter described above was the inability to provide an acceptable shear cut in some types of key blanks as used, for example, with certain Yale cylinder locks. Cutting of these key blanks required a rotating cutter as in the standard key duplicating machines.
Attempts to cut house keys with portable hand-operated code key cutters of the general type disclosed in U.S. Pat. No. 3,633,451 have been unsuccessful. The same is true of special code cutters of the type shown in U.S. Pat. No. 4,468,994. Such code key cutters are well suited for cutting ordinary automobile keys, but they cannot provide the reliable precision cutting required for modern house-key cylinder locks.
Modern cylinder locks are designed with security in mind and require keys cut to close tolerances. A high-quality duplicating key cutter with a rotary cutter can cut house keys within a tolerance range of 0.005 inch and provides precision cuts which are acceptable for most brands of cylinder locks. Heretofore hand-operated code cutters could not provide such precision cutting. Attempts to provide satisfactory cutting of house keys using auto-key code cutters of the type disclosed in U.S. Pat. No. 3,633,451 and U.S. Pat. No. 4,468,994 have been unsuccessful. Prior to the present invention it was assumed that hand-operated code key cutters similar to those used for cutting automobile keys could not provide the precision cutting required by locksmiths for servicing of security locks of the type used in modern motels and office buildings.
For the reasons mentioned above, the problems of locksmiths in cutting house keys by code have heretofore remained for many years without a practical solution.
Special electric machines are available commercially which are designed for code cutting and which employ motor-driven rotating key cutters as used in the duplicating machines. These machines provide the precision cutting required for modern cylinder locks but require a substantial capital investment. They do not provide the portability, convenience and versatility needed to permit a rapid, efficient, on-site key change at a typical office, apartment or motel room (See U.S. Pat. No. 4,521,142).